The present invention relates to web drive systems. In particular, the present invention relates to web drive systems which allow an operator to accurately and rapidly position a photographic film or photographic print paper web in a photographic system such as a film or paper cutter.
In the photographic processing business, there is need for web drive systems which drive photographic film or photographic print paper by accurate distances. One particularly important application for such web drive systems is the field of photographic film cutters.
In commercial photographic processing operations, very high rates of processing must be achieved and maintained in order to operate profitably. In addition, quality of processing and care for the customer's film must be maintained at extremely high levels. These requirements apply particularly to the cutting of rolls of film into strips which will fit into the envelopes in which individual customers receive their orders.
In commercial film processing, as many as 500 to 1,000 rolls of 12, 20, and 36 exposure film are initially spliced together for processing and printing purposes. For a time during processing, the individual rolls of film lose their identity as part of a single, large roll. After prints have been made from the photographic film, the individual customer's film must be separated from the large roll of film and cut into strips of several frames each so that the strips can be placed flat in an envelope together with the prints.
The step of cutting the film into strips and cutting the film at splices to separate individual customer orders must be done very accurately. All cuts must be made between individual frames so that no picture is damaged.
A co-pending patent application, Ser. No. 627,526 filed Oct. 31, 1975, by Victor R. Baert and Ronald B. Harvey, which is assigned to the same assignee as the present application, describes a highly advantageous automatic web advancement and cutting system. In the system described in the Baert and Harvey application, indicia on the film are sensed by the advancement and cutting mechanism, and the feed length required to position the film correctly in relation to the cutting mechanism is determined by the indicia sensed.
Other film cutting apparatus which sense perforations or notches in the film and the splices between film rolls include U.S. Pat. Nos. 3,763,728 by Blackman and 3,793,915 by Hujer.
In these automatic film cutters, as well as in semiautomatic and manual film cutters there is a need for a web drive system which will allow the operator to adjust the position of the film rapidly and accurately. For example, the operator may need to move the film slightly in either the forward or reverse direction to facilitate original calibration or set-up of the cutter. Any adjustment of film position, therefore, must be very accurate. In addition, at the beginning of a roll of film, there may be a considerable length of leader or blank film. It is desirable for the operator to be able to rapidly advance the film past the leader so that normal operation of the cutter may begin.